The present invention relates generally to fasteners and more particularly to insert fasteners adapted for securement within an opening in a panel by a threaded member.
Insert fasteners are well known in the art and are commonly used in the automotive industry to secure objects, such as interior trim, stereos, stereo speakers and/or glove compartments, onto a panel, such as an automotive body door panel and/or a dash panel.
Insert fasteners are used to secure an object onto a panel in the following manner. Specifically, the insert fastener is typically pushed into a square-shaped opening which is punched, molded or formed in the panel, the panel typically being manufactured out of a soft sheet metal or plastic. With the insert fastener disposed within the opening in the panel, the object is positioned against the panel. A threaded member, such as a screw, is then driven through the object and into threaded engagement with the insert fastener, thereby securing the object onto the panel. In the automotive manufacturing process, the threaded member is commonly driven through the object and into the insert fastener using automatic screw driving devices which typically have torque levels that are set for larger threaded members (approximately 5 Newton-meters).
One type of insert fastener which is well known in the art is the snap-in insert fastener.
Snap-in insert fasteners, also commonly referred to as snap-in fasteners, typically comprise one or more resilient fingers which are adapted to flatten as the fingers are pressed into the aperture in the automotive panel. Once the fingers pass through the aperture and onto the opposite side of the panel, the fingers outwardly snap back to their original configuration to lockingly secure the fastener onto the automotive panel.
Snap-in fasteners of the type described above are often constructed out of a solid, molded plastic which includes a central bore therethrough. In use, self-threading screws are typically driven in the central bore and into threaded engagement with the fastener.
As an example of a snap-in fastener, in U.S. Pat. No. 5,593,263 to J. P. Clinch et al, there is disclosed a snap-in fastener that is adapted to having an object such as automobile trim secured thereto by a threaded member such as a screw. The snap-in fastener features a pair of opposed resilient fingers having a contoured cross-section which enable them to flatten as they are pressed into an aperture in a panel. The fingers flatten as they are pressed into the panel aperture until free-ends of tabs extending therefrom spring or snaps outwardly to engage the opposite side of the panel to lockingly secure the fastener and the trim to the panel while enabling the fingers to resume their original contoured cross-sectional configuration.
Although well known and widely used in commerce, snap-in insert fasteners experience some notable drawbacks.
As a first drawback, virtually all known snap-in fasteners are "one-way" fasteners. As a result, once inserted into a panel opening, snap-in fasteners are not removable without destroying the fastener or the panel.
As a second drawback, some types of snap-in insert fasteners require a high level of force in order to remove the fastener from the panel. Consequently, the snap-in insert fasteners are effectively incapable of being backed out of the opening in the panel without destroying the shape of the aperture in the panel or destroying the functionality of the fastener itself. Because the snap-in fasteners can not be backed out of the aperture in the panel, the fasteners are rendered incapable of reuse or replacement. This is particularly significant with regards to snap-in fasteners that are constructed of plastic. Specifically, it has been found that automatic screw driving guns, which are routinely used on the assembly lines of automobile manufacturers, drive the threaded member into the fastener at such a high torque (approximately 5 Newton-meters) that the plastic fastener can become stripped as the threaded member is driven through the central bore. As a result, the stripped plastic fastener is unable to hold the screw, thereby rendering the plastic fastener useless. Because the stripped plastic fastener is incapable of being backed out of the door panel, the fastener has to be knocked into and through the panel aperture in order to remove the stripped plastic fastener. By knocking the plastic fastener into the panel, the insert is irretrievably lost within the interior of the automotive panel. Positioned free within the interior of the automotive panel, the insert tends to bounce around and can rattle within the automobile, thereby creating unwanted noise.
As a third drawback, it has been found that the tight, snap-fit securement of snap-in insert fasteners within an associated opening in the automotive panel limits the range of potential applications in which the fastener can be used. In particular, the snap-fit mechanics of a snap-in insert fastener allows for the fastener to be used only in conjunction with automotive or other panels having apertures of limited sizes and in conjunction with automotive panels of limited thicknesses.
As a fourth drawback, it has been found that snap-in insert fasteners require a relatively high insertion force (approximately 10 pounds) in order to push the fastener into the opening in the automotive panel. As a result, the entire manufacturing process of securing the object onto the panel is rendered more difficult and time consuming.
Another type of insert fastener which is well known in the art is the expansion insert fastener.
Expansion insert fasteners, also commonly referred to as expansion fasteners, typically comprise a pair of resilient legs and a central bore which is adapted to receive a threaded member. With the expansion fastener pressed into an aperture in an automotive panel, the threaded member is driven into the bore of the expansion fastener until the threaded member spreads the pair of resilient legs apart and into engagement against the panel, thereby securing the fastener within the opening in the panel.
As an example of an expansion fastener, in U.S. Pat. No. 5,873,690 to M. R. Danby et al, there is disclosed a thread nut expansion fastener for securement within an opening to a panel by a threaded member. When the threaded member is rotationally advanced through a barrel nut, the threaded member causes the free-ends of resilient legs to move away from each other and engage and urge resilient fingers into contacting engagement with opposite sides of the opening with sufficient force to secure the fastener to the panel.
Although well known and widely used in commerce, expansion fasteners experience some notable drawbacks. For example, it has been found that the complex bending arrangement of the legs of expansion fasteners renders the manufacturing of expansion fasteners a relatively complicated and expensive process.
Other types of fasteners which are well known in the art and are commonly used to secure an object onto a panel are mechanical clinch nut fasteners and mechanical weld nut fasteners.
Mechanical clinch nut fasteners typically comprise a metallic insert fastener which is disposed into an aperture formed in a soft metal automotive panel. With the fastener disposed within the aperture in the panel, a hydraulic machine is used to permanently clinch the metal of the insert fastener onto the metal of the automotive panel.
Mechanical weld nut fasteners typically comprise a metallic insert fastener which is disposed into an aperture formed in a soft metal automotive panel. With the fastener disposed within the aperture in the panel, a welding tool is used to permanently weld the metal of the insert fastener onto the metal of the automotive panel.
Although well known and widely used in commerce mechanical clinch nut fasteners and mechanical weld nut fasteners experience some notable drawbacks.
As a first drawback, mechanical clinch nut fasteners and mechanical weld nut fasteners are permanently affixed to its associated automotive panel and, accordingly, are incapable of replacement. Consequently, if the fastener were to become stripped, there would be no means for securing the object to the panel.
As a second drawback, mechanical clinch nut fasteners and mechanical weld nut fasteners require that an operator individually affix each fastener onto its associated panel using a clinching tool or a welding tool, respectively. As a consequence, utilization of mechanical clinch nut fasteners and mechanical weld nut fasteners is expensive and highly labor intensive.